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Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
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Coherent structural trapping through wave packet dispersion during photoinduced spin state switching
Henrik T Lemke1,2, Kasper S Kjær3,4,5, Robert Hartsock1,3
1Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Nature Communications
|May 25, 2017
Summary
Ultrafast X-ray spectroscopy reveals light-induced spin-state trapping dynamics in [Fe(bpy)3]2+. Molecular breathing and vibronic coupling were observed beyond the Born-Oppenheimer approximation.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Spectroscopy
Background:
- Ultrafast nonadiabatic chemical dynamics are challenging to describe due to coupled electronic and nuclear configurations.
- The Born-Oppenheimer approximation limits independent treatment of electronic and nuclear motion.
Purpose of the Study:
- To experimentally investigate light-induced spin-state trapping dynamics in [Fe(bpy)3]2+.
- To gain insights beyond the Born-Oppenheimer approximation using advanced spectroscopic techniques.
Main Methods:
- Time-resolved X-ray absorption spectroscopy (TR-XAS) with sub-30-femtosecond resolution.
- High signal-to-noise ratio measurements for detailed dynamic analysis.
Main Results:
- Distinguished electronic decay from structural trapping dynamics.
- Identified a coherent oscillating wave packet (265 fs period) as molecular breathing.
- Revealed intramolecular vibronic coupling and energy dissipation to the environment.
Conclusions:
- Modern TR-XAS provides crucial data for unraveling dynamic details of photo-functional molecules.
- Experimental insights beyond the Born-Oppenheimer approximation are achievable for complex systems.
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